Find-UnusedFilename

find-unusedfilename.ps1

function Find-UnusedFilename
{
    param (
        [string]$folder,
        [string]$filename
    )
    if (-not (Test-Path (Join-Path $folder $filename)))
    {
        return Join-Path $folder $filename
    }
    $counter = 1
    $ext = [System.IO.Path]::GetExtension($filename)
    $basename = [System.IO.Path]::GetFileNameWithoutExtension($filename)
    do
    {
        $filename = "$basename-$counter$ext"
        $counter++
    } while (Test-Path (Join-Path $folder $filename))
    return Join-Path $folder $filename
}